Spark plug



Aug; 2S, 12942. T. J. sMuLsKl SPARK PLUG Filed sept. 5. 1940 /NvE/vro lf/rendere J'm /ri ATTORNF.

Patented Aug. 25, 1942 SPARK PLUG Theodore J. Smulski, Gary, Ind.; assignor to Productive Inventions, Inc., a corporation of Indiana Application September-3, 1940, Serial No. 355,123

7 Ciaims.

MyV invention relates to spark plugs for the ignition systems of internal combustion engines and more particularlyvto a type of spark plugV which is provided with means for selectively determi-ning the heat range of the spark plug.

Heretofore the heat range of a spark plug more commonlyhas been determined by molding the central'electrode insulator so that the distance from the sparking' terminal of a central electrode to the seat of the electrode insulator would be greater in a hot'spark plug than in a cold spark plug. Such an arrangement requires that in the manufacture of spark plugs different types of central electrode insulators must be made and also correspondingly different sparkplug shells in order to provide spark plugs of different heat ranges in any particular size lofspark plug. It would be of considerable economic advantage if in the manufacture of'spark plugs the'number of different size parts could be materially reduced without reducing the numberof heat ranges covered by the line of spark plugs manufactured; It is, therefore, an object of my invention to provide a new and improvedspark plug constructionY which will overcome certain limitations of the arrangements of the prior art and which will be simple and easy to manufacture.

Another object of my invention is to provide a new and' improved spark plug the heat vrange of which may be readily and selectively determined.

is located in the proximity ofthe sparking teri minal of the central electrode and which is adjacent to and surrounds theportion of the frustoconical portion of the central electrode insulator is of heat conductive material so that by conducting the heat away from the vicinity ofthe lower end of the spark plug insulator,- the heat range of the spark plugmay be selectively predetermined.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims. Myinvention itself, however, both as to its organization and method of operation together with further objects and advantages thereof, will be better understood by reference to the following description 55 (Cl. 12B-169) taken in connection with the accompanying drawing, in which Fig. 1 is a cross-sectional View of the lower portion of a spark plug embodying my invention; Fig. 2 is a view of the lower portion of the spark plug insulator and the associated taper sleeve for a different heat range; Fig. 3 showsstill another View of the lower portion of a spark plug insulator with a taper sleeve for a hotter heat range spark` plug.

Referring to Fig. l of the drawing, I have shown therein the application of my invention to a spark plug of the type shown and described in my copending application, S. N. 345,474, filed July 15, 1940, and which is assigned to the same assignee as the present application. While I have shown the application of my invention to a spark plug of this type, it is of course to be understood that my invention is readily applicable to the sparkplugs of other types. In this figure, the lower portion of the spark plug shell I0 is provided with a bearing surface I I for supporting a, gasket.

I 2 upon which the central electrode insulator I3 is supported. This arrangement is similar to that found in spark plugs more commonly in use today. The central electrode insulator I3 supports the central electrode I4 having a sparking terminal Iii adjacent to the lower end of the spark plug. The sparking terminal I5 cooperates with the ground electrode Iwhich isvarranged so as to provide a taper gap in accordance with the teachings of my copending application referred to above. The ground electrode I5 extends through an aperture in a relatively thin wall I'I so that a chamber is formed in the lower portion of the spark plug shell It. Within this chamber there is provided a taper sleeve ES which is provided with a flange IS which engages a bearing surface 2! which surface is closely adjacent to the bearing surface i for the gasket In order to insure that the ange I ti of the taper sleeve I8 is in good heat conductive relation with respect to the spark plug shell I Q and the bearing surface 2o thereof, it is preferable to have the insulator gasket I2 of sufcient size so as to slightly overlap the upper portion of the flange IS.' This insulator gasket which is generally-of soft material, such as copper, will permit good seating of the insulator I3 and yet will apply sufficient pressure to the flange I9 to insure good heat conduction of the taper sleeve I8 with respect to the spark plug shell I0.

In the arrangement shown in Fig. l, the lower portion of the spark plug insulator i3 has a generally frusto-conical portion which is surrounded by the taper sleeve I8 the inner surface ci which.

is substantially complementary in shape to the frusto-conical portion of the insulator I3. While this particular shape has been shown for purposes of illustration in Fig. 1, it is to be under stood that if the lower portion of the spark plug insulator I3 has a somewhat similar configuration, that the taper sleeve I 8 will likewise have a different internal configuration which is substantially complementary in shape to the adjacent spark plug insulator portion. It will be noted in the drawing, that the heat conductive taper sleeve member I8 is closely adjacent to the spark plug insulator I3, but that it does not necessarily make actual Contact therewith. For the purposes of clear illustration, this slight separation, which in actual practice amounts to a few thousandths of an inch, has been greatly exaggerated in the drawing. It is further to be understood that while the spark plug of the type shown, described and claimed in my copending application has a spark plug shell Iil provided with a tapered wall inner chamber, that where a straight wall inner chamber is provided that the distance from the outside of the heat conductive sleeve member IS to this wall of the inner chamber does not prevent the taper sleeve I8 from determining the heat range of the spark plug. In order to determine what heat range is to be desired in the manufacture of spark plugs of this type, it is merely necessary to provide the spark plug shell with means for receiving one of a plurality of lheat conductive taper sleeve members to selectively predetermine the heat range of the spark plug. In Fig. 1 the spark plug is considered to be of the cold type because of the greater length of the taper sleeve member I3. In Fig. 2 there is shown a taper sleeve ISa in operative relation to the spark plug insulator I3 and an insulator gasket I2, and this taper sleeve is somewhat shorter thus producing a hotter spark plug. In Fig. 3 again there has been shown a taper sleeve ISb of still smaller dimensions in operative relation to the spark plug insulator I3 and the gasket I2, and in this manner a still hotter plug may be provided. While I have shown for purposes of illustration three different lengths of tapered sleeve I8, it will be readily understood that any other number may be provided dependent upon how many heat ranges are desired and as to what degree of separation is deemed necessary between each of the different heat ranges.

It is believed that to those skilled in the art it is readily obvious that the arrangement just described oers considerab-le economy in the manufacture of spark plugs since for each thread size of spark plug a single size insulator may be utilized. In some instances, several thread sizes of spark plugs may be utilized in the same size insulator. In making recommendations as to the particular heat range of spark plugs for a given automotive engine, a manufacturer generally recommends a spark plug having a heat range adapted to average operating conditions. In the replacement of spark plugs, it frequently occurs that the recommended type of spark plug is not best suited to the general driving conditions of this particular automotive vehicle, which for eX- ample may be prolonged high speed driving, or in another case much starting and stopping, and it is then necessary to remove these spark plugs and insert a different set of another heat range. By utilizing spark plugs of the type described above, it would be unnecessary to discard such spark plugs since by merely inserting a diierent type of taper sleeve, the spark plugs may be adjusted so as to have the proper heat range characteristics best suited for operation of this particular automotive vehicle. Obviously such an arrangement again provides economies for the operator of the vehicle.

While I have shown and described my invention in connection with certain speciiic embodiments and as applied to a particular type of spark plug, it will, of course, be understood that I do not wish to be limited thereto, since it is apparent that the principles herein disclosed are susceptible of application to many different types of spark plugs and modifications may be made in the instrumentalities employed and the arrangement thereof without departing from the spirit and scope of my invention, as set forth in the appended claims.

What I claim as new and desire to secure as Letters Patent of the United States is:

l. In a spark plug, the combination of a central electrode insulator having a frusto-conical shape in the proximity of the sparking terminal of the central electrode, a taper sleeve heat conductive member located adjacent to and surrounding a portion of the frusto-conical portion of said insulator, said taper sleeve having a predetermined length to determine the heat range of said spark plug, a shell having a relatively thin en-d wall provided with a single opening, said shell being provided with a bearing surface for a gasket supporting said insulator, said shell being provided with a second bearing surface for receiving said taper sleeve, said second bearing surface being of a lesser diameter adjacent to said first bearing surface, and an insulator supporting gasket overlapping said taper sleeve to retain it in good heat conductive relation to said shell.

2. In a spark plug, the combination of an insulator carrying a central electrode, said insulator in the vicinity of a sparking terminal having a frusto-conical shaped portion, a shell for said insulator having a relatively thin end wall provided with a single opening, said shell having a bearing surface, a taper sleeve having a certain length for determining the heat range of said spark plug, said taper sleeve being mounted on said bearing surface, said taper sleeve being located adjacent to said frusto-conical portion of said insulator, and a gasket for said insulator mounted to maintain said taper sleeve in good heat conductive relation with respect to said shell.

3. The combination of a spark plug having a shell provided with a relatively thin end wall having a single opening, said shell having a bearing surface for receiving a gasket, a second bearing surface of lesser diameter located adjacent said first bearing surface for receiving one of a plurality of heat conductive taper sleeves to determine the heat range of said spark plug, a heat conductive taper sleeve mounted on said latter bearing surface, a gasket mounted on said iirst surface and extending sufficiently to contact a portion of said heat conductive taper sleeve, and an insulator mounted on said gasket, said insulator having a portion closely adjacent to said heat conductive taper sleeve.

4. In a spark plug, the combination of a central electrode insulator, a heat conductive member located adjacent to and surrounding a portion of said insulator in the proximity of the sparking terminal of said central electrode, said heat conductive member having a predetermined length to determine the heat range of said spark plug and having an internal surface substantially complementary to the surface of the adjacent insulator, and a shell for said insulator and said heat; conductive member, said shell having a tapered inner Wall and a relatively thin end Wall with a single opening therein to form a restricted chamber for said insulator and said heat conductive member, said heat conductive member being arranged to be in good heat conductive relation with respect to said shell, and a gasket cooperating with said shell for maintaining said insulator and said heat conductive member in operative relation with respect to each other and in respect to said shell.

5. In a spark plug, the combination of an insulator carrying a central electrode, a shell for said insulator having a relatively thin end wall provided With a single opening, said shell having a bearing surface, a heat conductive member having a certain length for determining the heat range of said spark plug, said heat conductive member being mounted on said bearing surface so as to be in good heat conductive relation to said shell, said heat conductive member being located adjacent to and surrounding a portion of said insulator in the proximity of the sparking terminal of said central electrode, said heat conductive member having an internal shape generally conforming to the shape of said adjacent insulator portion.

6. In a spark plug, the combination of a central electrode, an insulator therefor, a shell therefor having a relatively thin end wall and being provided with means for supporting said insulator, said shell forming a restricted chamber surrounding the lower portion of said insulator, means provided within said shell adjacent said insulator supporting means for receiving one of a plurality of diierent heat conductive sleeves, and a heat conductive sleeve mounted within said shell in good heat conductive relation to said shell, said sleeve having an internal surface substantially complementary to a portion of said insulator Within said chamber and being located closely adjacent to said insulator and extending into said chamber for a predetermined distance to determine the heat range of said spark plug.

7. In a spark plug, the combination of a central electrode, an insulator therefor, a shell therefor provided with means for supporting said insulator, said shell having a relatively thin end Wall provided with a single opening thereby forming a restricted chamber surrounding the lower portion of said insulator, means provided within said shell for receiving one of a plurality of different heat ccnductive members, and a heat conductive member mounted within said shell adjacent said means for supporting said insulator and in good heat conductive relation to said shell, said member being located closely adjacent to said insulator and extending into said chamber for a predetermined distance to determine the heat range of said spark plug.

THEODORE J. SM'ULSKI. 

